NEW YORK, Oct 10 (Reuters) - U.S. Senator Elizabeth

Warren has asked antitrust regulators to closely scrutinize a

$16.5 billion deal in which Novo Nordisk's

controlling shareholder would acquire contract drug manufacturer

Catalent ( CTLT ), saying it may give the pharmaceutical company

an unlawful advantage in weight loss and obesity drugs.

Novo Holdings, the investment firm that has a controlling

interest in Novo Nordisk, signed a $16.5 billion deal to buy

Catalent ( CTLT ) in February to boost supply of Wegovy, Novo's

blockbuster GLP-1 weight loss drug.

Warren urged the U.S. Federal Trade Commission to sue to

block the deal if the regulator finds it illegal - which could

delay the deal's expected closing later this year.

"I am concerned that Novo Nordisk's merger with Catalent ( CTLT )

will give Novo Nordisk unprecedented visibility into and control

over its competitor's production capacity, costs, and business

practices, and the ability to preference its own products and

obstruct its competitors' use of Catalent ( CTLT ) to produce GLP-1

drugs," Warren said in the letter.

Warren has been a political ally and supporter of FTC Chair

Lina Khan, who some business groups have criticized, saying she

is over-eager to block deals. Khan has said only a small

fraction of deals the FTC reviews are ultimately challenged.

Eli Lilly's GLP-1 drugs - Zepbound approved for weight loss

and Mounjaro for diabetes - compete with Novo Nordisk's Wegovy

and Ozempic.

Lilly also uses Catalent ( CTLT ) for GLP-1 and diabetes drug

production.

David Ricks, Lilly's CEO, has criticized the deal. He told

investors in August that while Lilly is building its own sites,

the company is concerned by "the oddity of your main competitor

being also your contract manufacturer and how to resolve that

situation."

Demand for GLP-1 weight loss drugs in the U.S. has

outstripped supply, leading to shortages and a rise in

compounded versions that are created by combining, mixing, or

altering drug ingredients.

Both Novo and Lilly GLP-1 drugs have experienced shortages

during the last two years and one dose of Novo's Wegovy remains

on the FDA's shortage list.

Under President Joe Biden, the FTC has sought to block

vertical mergers it thinks would allow the merged company to

block competitors' access to supply chains or distribution

points, or hand over sensitive competitive data.